Induction heating coil unit



Oct. 8, 1957 R. s. sEGswoRTH INDUCTION HEATING COIL UNIT Invznftor Roar/er s. sscswonm Attys FIG.2

Filed June 8, 1955 IIIII. .....w W Q /o.. Moe. d, wenn J MyW/u im i ,w ....M M m nu.

ZJ/fgj//w FIG. I

FIG.3

INDUCTION HEATLNG conJ UNrT Robert Sidney Segsworth, Toronto, Ontario, Canada, as-

signor tol The General lEngineering Company Limited, Toronto, Ontario, Canada Application .lune 8, 1955, Serial No. 514,057

3 Claims. (Cl. 219-10.67)

This invention relates to an induction heating coil construction for use in the continuout heating of relatively large pieces of metal such as steel bar, ingots, and the like.

The object of the invention is to provide an induction heating coil construction arranged for the continuous heating of heavy stock, i. e., bar, ingot and the like, and of a capacity to give continuous service in providing adequate support for the coil windings and for stock passed therethrough.

With the foregoing and other objects in view the invention relates to a construction generally comprising an induction heating coil embedded in a rigid mass of nonmagnetic heat resistant insulating material and having therewithin an axially extending heating chamber the walls of which are formed of a material of high temperature resistance and preferably of high electrical resistability; the said chamber also preferably including replaceable wear plate means adapted to serve as a member over which stock is passed through the chamber during heating.

The invention will be appreciated in more detail by reference to the accompanying drawings and the following specification describing a preferred construction.

In the drawings:

Figure 1 is an axial section of an induction heating coil construction of the invention.

Figure 2 is a perspective view of an assembly of a plurality of coils as shown in Figure l,

Figure 3 is a section through the line 3-3 of Figure 2.

Referring to the drawings, the induction heating coil construction of the invention comprises the induction coil windings 1t) of any conventional form taped and bound with electrically insulating material impregnated with insulating varnish of high heat resistance, and further bound endwise with glass tape, impregnated with insulating varnish, and baked according to known practice.

Thus bonded induction coil assembly 11 contains a liner 12 preferably conforming to the interior shape of the coil but annularly and inwardly spaced therefrom by a layer of fibrous insulator packing 13 preferably formed of aluminum silicate fibre produced by the Carborundum Company of Niagara Falls, New York, under the name Fiberbrax.

The liner 12 is formed of stainless steel of high temperature resistance and relatively high electrical resistivity or of a refractory material depending upon the application and according to known principle. When using 60 cycle energizing current for the induction heating coils the walls 14 of the liner should be about 1A@ of an inch thick. While a split liner has been employed the invention contemplates the formation of a seam weld 15 whereby the liner 12. takes the form of a seamless tube. By this means the formation of an insulating joint at the split of the former split liner is avoided and a more sturdy construction is accomplished,

atent M 2,809,263 Patented Oct. 8, 1

lCC

In manufacture, the coil assembly 11 is supported in a suitable form or mould into which is poured a cas'able refractory cement to form an embedding casing 16 of massive form of a non-magnetic heat resisting material. After the castable refractory material has set, the liner 12 is assembled in place and the annular space between the liner and inside of the coil is packed with a fibrous thermal insulating material4 13 or alternatively a light weight castable refractory with high thermal insulating properties. if the liner 12 is formed of stainless steel the packing material must be resilient fibrous material to avoid buckling of steel liner with expansion, but if a refractory liner is employed the packing material may be either the fibrous material or a thermal insulating castable refractory. The result is a cast refractory of massive unitary form in which the induction heating coil assembly is rigidly embedded and held firmly against vibration. The simple shape of the unit enables easy handling and assembly with other similar units as shown in Figure 2; the aligned coil units 17, 18 and 19 containing continuous wear strips 20a extending therethrough and resting .Jpon the bottom faces of the tubular liners. The wear strip is preferably formed of a material of low magnetic permeability such as stainless steel.

The induction heating coils of each assembly or single coil, as the case may be, may be formed of copper tubing or the like through which a cooling medium may be passed. Power is supplied through the connecting bars l and a suitable coolant connection are provided at 22. The liner 12 of each of the coil units is turned over at the ends to form retaining flanges 23 and 24 as indicated in Figures l and 2. Thus each induction heating coil unit of the invention is complete as to supporting structure and structural integrity against vibration, requiring only a suitably supporting base to maintain it in alignment, aside from the usual power and coolant connections.

I claim:

l. An induction heating coil unit for heating relatively heavy stock and comprising, in combination: a cast mass of refractory material having an axial opening therethrough; an induction heating coil embedded entirely within said mass and formed of a plurality of turns of a conductor extending coaxially with the opening in said mass and substantially the full length thereof; a seamless tubular liner formed of a material of high electrical resistivity and extending over the inner surfaces of said opening to serve as a wearing surface over which material to be heated may be passed through said unit; and a fibrous insulating packing embedded in the inner surfaces of said opening and disposed between said surfaces and said liner to provide a vibration absorbing support therefor.

2. An induction heating coil unit for heating relatively heavy stock and comprising, in combination: a cast mass of refractory material having an axial opening therethrough; an induction heating coil embedded entirely within said mass and formed of a plurality of turns of a conductor extending coaxially with the opening in said mass and substantially the full length thereof; a seamless tubular liner formed of a metal of high electrical resistivity and extending over the inner surfaces of said opening to serve as a wearing surface over which material to be heated may be passed through said unit; and a fibrous insulating packing embedded in the inner surfaces of said opening and disposed between said surfaces and said liner to provide a vibration absorbing support therefor.

3. An induction heating coil unit for heating relatively heavy stock and comprising, in combination: a cast mass of refractory material having an axial opening there- 3 through; an induction heating coil embedded entirely References Cited in the file of this patent within said mass and formed of a luralit of turns of a conductor extending coaxially Witllij the ogening in said UNITED STATES PATENTS mass and substantially the. full length thereof; a seam- 1,309,463 Bornand et 211- June 9, 1931 less tubular liner formed of stainless steel and extending 5 1,893,380 USChmaIl et 31- 12ML 3, 1933 over the inner surfaces of said opening to serve as a wear- 2,325,633 Strickland Allg- 3, 1943 ing surface over which material to be heated may be 2,716,695 Cllff 61211 Allg. 30, 1955 passed through said unit; and a fibrous insulating packing embedded in the inner surfaces of said opening and dis- FOREIGN PATENTS posed between said surfaces and said liner to provide a 10 540,969 Germany Dec. 10, 1931 vibration absorbing support therefor. 675,969 France Feb. 17, 1930 

